Blog | Monday, October 15, 2012

Ninth hantavirus case linked to Yosemite

In 1993 in the Four Corners region of the American Southwest, a woman developed a cough and progressive shortness of breath and died shortly thereafter. A few days later, her fiancee, a young physically fit man developed similar symptoms was rushed to a hospital and also died. A series of laboratory tests failed to identify any known infectious agent. The Centers for Disease Control and Prevention (CDC) Special Pathogens Branch was notified. Further testing revealed a previously unknown strain of hantavirus. The new strain would eventually be named Sin Nombre hantavirus (perhaps the most paradoxical name I've ever encountered).

In Asia and Europe hantavirus infections in people cause a very different illness marked by hemorrhagic fever and kidney failure. This new illness in the U.S. marked by progressive respiratory failure was named Hantavirus Pulmonary Syndrome (HPS). HPS has early symptoms that are very similar to the flu: fever, fatigue, and muscle aches in the thighs and back. About half the patients also experience headaches, chills, nausea, vomiting, and diarrhea. Four to 10 days after the initial symptoms a cough and progressive shortness of breath develop. The lungs fill with fluid. About one third of patients with HPS die.

Since 1993 there have been very few (587) cases of HPS nationwide. The hantavirus strains in the U.S., like elsewhere, are carried by rodents. Sin Nombre hantavirus is carried mostly by the deer mouse in the western and central U.S. and Canada. People are infected with hantavirus through contact with infected rodents, or their urine and droppings. Hantavirus in the U.S. cannot be transmitted from person to person.

This summer hantavirus claimed the spotlight because of a number of cases linked to Yosemite National Park. Nine visitors to Yosemite have become sick from hantavirus, the most recent this week. Most of them camped in tent cabins in Curry Village in early July. These cabins have since been closed. Three of the nine have died.

The park, along with state and national health agencies, have attempted to contact all campers who have visited Yosemite this summer to advise them to seek care promptly if they develop flu-like symptoms. There is no specific treatment for hantavirus, but prompt admission to intensive care can help support patients on ventilators until the illness resolves. The patients who have survived seem to have recovered completely.

For those of us who haven't been to Yosemite recently, the CDC advises that the best way to avoid hantavirus is to keep your home and nearby structures (garages, sheds) free of rodents. The links below have some common-sense suggestions.

Our family's rodent control strategy involves an attractive feline named Pancho. Perhaps we should make her available to the National Park Service.

Learn more:
Hantavirus in Yosemite: Ninth case reported in another visitor (Los Angeles Times)
August 2012 – Yosemite National Park Outbreak Notice (CDC)
(CDC information page)
Tracking a Mystery Disease: The Detailed Story of Hantavirus Pulmonary Syndrome (CDC)

Albert Fuchs, MD, FACP, graduated from the University of California, Los Angeles School of Medicine, where he also did his internal medicine training. Certified by the American Board of Internal Medicine, Dr. Fuchs spent three years as a full-time faculty member at UCLA School of Medicine before opening his private practice in Beverly Hills in 2000. Holding privileges at Cedars-Sinai Medical Center, he is also an assistant clinical professor at UCLA's Department of Medicine. This post originally appeared at his blog.